Video: Freshwater factor on oceans

By Miguel Llanos Reporter
msnbc.com
updated 4/5/2011 1:47:48 PM ET 2011-04-05T17:47:48

A swirling pool of icy Arctic meltwater has the potential to flush quickly into the Atlantic Ocean and alter weather in Northern Europe, climate scientists reported Tuesday.

Located just north of Alaska and Canada, the vast pool's percentage of freshwater from rivers has grown by about 20 percent since the 1990s and that change in salinity level could impact ocean circulation and cause temperatures in Northern Europe to cool, the experts said.

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That level of increase in Arctic freshwater has never before been observed by scientists, Laura de Steur, an oceanographer with the Royal Netherlands Institute for Sea Research, told msnbc.com.

"The volume of water discharged into the Arctic Ocean, largely from Canadian and Siberian rivers, is higher than usual due to warmer temperatures in the north causing ice to melt," she added in a statement released by European science institutes working together on climate projects.

"Sea ice is also melting quickly," she said, "another new record low for ocean area covered was documented this past January by the National Snow and Ice Data Center adding even more freshwater to the relatively calm Arctic Ocean."

About the volume of Lake Michigan and Lake Huron combined, the pool — known by scientists as the Beaufort Gyre — has been kept bottled up in the Arctic by a clockwise wind pattern that has not shifted in 12 years. Normally, the winds change at intervals of five to 10 years.

"When the general atmospheric circulation pattern does shift, the fresh, cold water is expected to enter the North Atlantic, with unpredictable impact on an ocean current system important to both European weather and marine food chain," according to the European institutes.

"Signs of such an atmospheric shift appeared in 2009 but the episode was too short to cause a major flush," they added.

De Steur noted that an additional factor is that more of the Arctic's sea ice is younger and thinner, not the older and thicker ice as in the past.

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That makes the ice "more mobile and could exit the Arctic faster," she said. "In the worst case, these Arctic outflow surges can significantly change the densities of marine surface waters in the extreme North Atlantic. What happens then is hard to predict."

"Large regional changes could be in store if the ocean circulation changes," she added.

"Atmospheric circulation in the Arctic has been changing and seems very variable over the last years and the natural seasonal circulation patterns appear to have been different too, so clearly research is needed to understand the present state, and possibly predict near-future changes," De Steur told msnbc.com.

A greater concentration of freshwater in the north Atlantic could slow down a giant ocean current "conveyor" known as the Atlantic Thermohaline Circulation.

That, in turn, could alter weather patterns in Northern Europe, creating cooler temperatures.

Rising air temperatures could temporarily mask the cooling. "However, the western edge of Europe, particularly the United Kingdom and Scandinavia, could cool substantially nonetheless," the European institutes stated.

Scientists do think that the water would not flush out if a wind pattern shift is shortlived.

"For a large release of freshwater to occur we expect that a change in circulation should be maintained for a longer time period than just one season, so for example a year or even longer," De Steur said.

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